Mixing apparatus

ABSTRACT

A mixing apparatus is provided that comprises a metal body having a central, vertical opening extending throughout its length. The opening has a circular horizontal cross section with the upper portion of the opening having a larger diameter than its lower portion. Positioned in the opening and extending throughout its length is a vertical, rotatable shaft. There is a mixing cup disposed in the upper, enlarged position of the opening, the cup having a hole in its bottom through which the shaft extends and in which the shaft is free to rotate. Attached to the shaft within the cup is a spiral rotor. The mixing cup is not free to rotate, but means are provided for raising and lowering the cup relative to the rotor. A heat exchange means associated with the body makes it possible to either heat or cool the mixing cup. A motor operatively connected to the lower end of the shaft provides means for rotating the shaft and the attached rotor. A glass dome having gas and liquid ports and an airtight means for introducing solids can be attached to the upper end of the mixing cup. The mixing apparatus is particularly suitable for use in mixing small quantities of elastomers and compounding ingredients under controlled conditions.

United States Patent [151 3,695,586 Griffin 51 Oct. 3, 1972 [54] MIXING APPARATUS [72] Inventor: Warren R. Griffin, 4949 Concordia [57] ABSTRACT CifCle, y Ohio 45440 A mixing apparatus is provided that comprises a metal body having a central, vertical opening extending [22] Flled' 1970 throughout its length. The opening has a circular [21] Appl. No.: 87,218 horizontal cross section with the upper portion of the opening having a larger diameter than its lower portion. Positioned in the opening and extending [52] throughout its length is a vertical, rotatable shaft. [51] Int Cl B0" There is a mixing cup disposed in the upper, enlarged [58] Fieid "n 259/4 position of the opening, the cup having a hole in its 259/7 8 24 44 6O 6 bottom through which the shaft extends and in which 3 the shaft is free to rotate. Attached to the shaft within the cup is a spiral rotor. The mixing cup is not free to rotate, but means are provided for raising and lower- [56] References Cned ing the cup relative to the rotor. A heat exchange UNITED STATES PATENTS means associated with the body makes it possible to either heat or cool the mixing cup. A motor operat1ve- 2,895,645 7/1959 Pelak ..259/43 X ]y connected to the lower end f the Shaft provides 2,688,470 9/1954 Marco ..259/8 means for rotating the Shaft and the attached roton A 2,778,922 1/1957 Birkner ..259/DIG. 18 glass dome having gas and liquid pol-ts and an airtight 2,513,035 6/ 1950 Lopata ..259/8 means for introducing Solids can be attached to the 2,867,997 1/1959 Lake ..259/l08 upper end of the mixing Cup The mixing apparatus is 3,338,560 8/1967 Katzer et al ..259/18 X Primary Examiner-Edward L. Roberts Assistant Examiner-Philip R. Coe Attorney-Harry A. Herbert, Jr. and Cedric l-l. Kuhn particularly suitable for use in mixing small quantities of elastomers and compounding ingredients under controlled conditions.

14 Claims, 4 Drawing Figures PATENTEDHCIB I972 3.695.586

SHEET 1 OF 4 PATENTEDBBTIB m2 7 3,695,586

SHEET 3 OF 4 I z-EVTOR. wa/mew 1e. sewn/v w w vii/2% FTTORNEEIJ MIXING APPARATUS FIELD OF THE INVENTION This invention relates to a mixing apparatus which is especially suitable for blending elastomeric polymers and compounding ingredients. In one aspect it relates to a mixer which is adapted to mix small amounts of materials under controlled conditions.

BACKGROUND OF THE INVENTION In the compounding of elastomers, the standard commercial types of mixers used are the roll mill and the Banbury mixer. These are large pieces of equip ment having a capacity, for example, of 400 to 500 pounds. Such equipment is, of course, unsuitable for use in research facilities where only small amounts of elastomers are generally compounded. In the past equipment for mixing research quantities of elastomeric polymers has been developed by miniaturizing the large industrial mixers with little or no change in design. The miniaturized mixers have not been entirely satisfactory with regard to temperature and shear control, maintenance of a desired environment surrounding the polymer, contamination of the polymer, and quantitative recovery of small batches. Furthermore, the prior art mixers are difficult to disassemble and clean, and are hazardous to operate.

It is an object of this invention, therefore, to provide an improved apparatus for mixing small quantities of elastomers and compounding ingredients.

Another object of the invention is to provide a mixer that ensures the quantitive recovery of the materials to be blended.

A further object of the invention is to provide a mixing apparatus that incorporates features making it possible to control the temperature of the mix as well as the shearing force exerted thereon and to conduct the mixing in a vacuum or a desired atmosphere.

Other and further objects and advantages of the invention will become apparent to thoseskilled in the art upon consideration of the following disclosure and the drawing in which:

FIG. 1 is an elevational view, partly in cross section, of the mixing apparatus of this invention;

FIG. 2 is a partial plan view of the mixing apparatus with upper rings of insulation removed;

FIG. 3 is a partial plan view of the mixing apparatus with the mixing cup and insulation removed; and

FIG. 4 is an elevational view, partly in cross section, illustrating the dome and its manner of attachment to the mixing cup.

SUMMARY OF THE INVENTION The present invention resides in a mixing apparatus that is particularly suitable for use in the laboratory in compounding small amounts of elastomer formulations. In elastomer research, experimental polymers are generally produced in small quantities because of the high costs involved. There is, therefore, a great need for a mixer for compounding research quantities of polymers to give a product that can reliably be evaluated to determine its potential. The mixing apparatus of this invention, which fulfills the need of the researcher, in a broad aspect. comprises a metal body member having a central, vertical opening extending throughout its length. The opening is circular, and its upper portion has a larger diameter than its lower portion to accommodate the positioning of a mixing cup therein. Disposed in the opening and extending throughout its length as well as through a hole in the bottom of the mixing cup is a vertical, rotatable shaft. The shaft is free to rotate in the hole in the mixing cup, but the cup itself is prevented from rotating. A spiral rotor is attached to the vertical shaft above the bottom of the mixing cup which can be raised and lowered relative to the rotor. Associated with the metal body is a heat exchange means, an arrangement of apparatus making it possible to control the temperature of the mixing cup. A motor operatively connected to the lower end of the shaft provides means for rotating the rotor at a desired speed of rotation. A glass container having gas and liquid ports and an air tight means for introducing solids can be attached to the upper end of the mixing cup.

A more comprehensive understanding of the mixing apparatus of this invention can be obtained by considering the drawing. Identical reference numerals are used in the several figures to designate the same elements. Referring first to FIG. 1, mixing apparatus 10 comprises a body member 11 which can be fabricated from any suitable metal. However, it is preferred touse brass because of its ease of machining, its corrosion resistance, and good heat transfer properties. A vertical opening, circular in horizontal cross section, extends through a central portion of the body, the upper portion 12 of the opening having a larger diameter than its lower portion 13.

A vertical shaft 16 is disposed in the opening and extends through its upper portion 12 and lower portion 13. The shaft is held in a rotatable position by means of two sets of tapered roller bearings 17 and 18. The upper set of bearings is disposed between a pair of races 19 and 21 which are in the form of rings tapered to conform to the taper of the roller bearings. Bearings 17 ride in a groove 22 constituting a bearing surface formed in the outer surface of race 19 which rests on circular shoulder 23 of shaft 16. Race 21 is positioned between the wall of the body opening and bearing 17 and in addition to functioning as a bearing surface maintains the bearings in groove 22. The upper set of bearings is maintained in position by means of retainer ring 24 which is threaded to the wall of the upper end of the lower portion 13 of the body opening so that the bottom of ring 24 rests on the top of race 21. The retainer ring has holes 26 in which a wrench having a projecting pins can be fitted to tighten or loosen the ring. Retainer ring 24 is screwed securely in place by applying a torque of 25 to 30 ft. lbs. thereto in order to ensure that there is no lateral movement of shaft 16.

The lower set of bearings 18 is disposed between a pair of races 27 and 28 which are identical in structure to races 19 and 21. However, as seen from the drawing, the actual placement of the bearings has been reversed so that the smaller ends of the upper and lower bearings face one another. As a result, the placement of the races has been reversed so that similar ends are opposite to each other. Race 28 tests on circular shoulder 29 formed at the bottom of the lower portion 13 of the body opening. As a result of this arrangement, race 28 holds bearings 18 in position in bearing groove 31 of race 27 which in turn is held against shaft 16 and its circular shoulder 32.

A container 33 is positioned in the enlarged upper portion 12 of the body opening. The container has an open top, and its exterior is cylindrical in shape. The diameter of the container is such that the lower portion of its sides are in sliding contact with the lower portion of the wall of enlarged opening 12. The container is not free to rotate, being held in position by a plurality of pins 34. The upper ends of the pins are pressed or fixed in position in vertical holes formed in the container and extending upwardly from and spaced around its base adjacent its periphery. The lower ends of the pins are positioned in vertical holes formed in body 11 and extendingdownwardly therethrough so as to be in vertical alignment with the container holes. The pins are free to move vertically in the holes formed in the body, and the length of each pin is shorter by a desired amount, e.g., 0.05 to 0.10 inch, than the total length of each pair of vertically aligned holes. The maximum amount that the container can be raised is controlled or limited by the position of the bottom of the rotor.

Shaft 16 extends upwardly through a central hole in the bottom of container 33 in which it is free to rotate. A sealing compound 37, preferably a fluorocarbon such as a Teflon fluorocarbon, fills the upper part of the space between the shaft and the hole in the container. The sealant is held in is held in position by means of retainer ring 38 which is threaded into the hole in the container. It is also within the scope of the invention to position a spring between retainer ring 38 and sealant 37 in order to ensure positive seating of the sealant. The spring can be in the form of a ring of low compression set rubber or a pair of metal rings separated by a plurality of coil springs.

A spiral rotor 39, which is shown only partly in cross section, is positioned in the container and is fixedly attached to the upper end of the shaft. It is noted that the sealant extends into a space 41 between the shaft and the lower portion of the rotor opening through which the shaft extends. The rotor is affixed to the shaft by a coupling device which consists of a circular disc or collar 42 having a central opening therein and two vertical, cylindrical pins 43 attached thereto. Grooves formed in the sides of the top of the shaft and in the wall of the top of the rotor opening when in coincidence form a pair of cylindrical openings. When the pins are in position as illustrated, the rotor and shaft are coupled to one another so that they will rotate together. The coupling device is held securely in position by means of rotor cap 44 having a bolt 46 attached thereto. The central opening in disc 42 permits the bolt to be threaded into the end of the shaft, thereby securing the coupling device. The rotor cap is conical in shape and is provided with projections or arms 47 to which a conforming wrench can be attached to tighten or loosen the cap.

The upper, external portion of container 33 is provided with threads 48 to which ring 49 having internal threads is threaded. Ring 49 is maintained in a fixed vertical position on container 33 by means of retainer ring 51 which is threaded onto threads formed in the vertical surface ofa recess in the upper end of body 11. The retainer ring is in contact with ring 49, thereby holding it in place against the horizontal surface of the aforementioned recess. Around the exterior surface of ring 49 are teeth which mesh with worm 52 which is horizontally disposed in an opening in body 11. Thus, ring 47 operates as a worm wheel for worm 52, the two elements together constituting a worm gear.

Body 11 is provided with a heat exchange means which functions to heat or cool the body as well as container 33 with which it is in sliding contact. As depicted in FIG. 1, the heat exchanger comprises a metal coil 53, preferably of copper tubing, positioned in a recessed section of the body wall, through which any suitable heat exchange medium, such as water, steam, or oil, is circulated. lnlet 54 is connected to the source (not shown) of the heat exchange medium which can include a pump and a means for heating or cooling the medium. Outlet 56 is behind inlet 54 so that it is not shown in FIG. 1, but it can be seen by referring to FIG. 2. It is to be understood that other types of heat exchange means can be employed. For example, where heating only is desired, an electrical heating coil can be used. In a preferred embodiment, a spiral groove is machined in the surface of the body and covered with a sheet metal material. This arrangement functions in the same manner as coil 53, i.e., the heat exchange fluid circulates continuously through the covered grooves. Since container 33 is in sliding contact with body 11 as previously described, heating or cooling of the container is primarily accomplished by the transfer of heat through the body. However, heat transfer also occurs through pins 34 and shaft 16.

The exterior of body 11 including coil 53 is encompassed by an insulating material 57. The insulation is, in general, formed in the shape of rings to facilitate their placement and removal from the body. As shown, the top and bottom rings are shaped differently from one another and from the middle rings that are of uniform configuration. Thus, uppermost ring 58 has a horizontal extension 59 which extends over the top edge or rim of the body to a point in proximity to the container. The lowermost ring 61 has an enlarged cross section as compared to the other rings and does not surround an upright part of the body. On the other hand, ring 61 covers at least a portion of the bottom of the body and provides a base on which the body rests. The rings immediately above bottom ring 61 are generally smaller in size of diameter or thickness so as to conform to the shape of the body or to permit the placement of the bolts 62. Thus, ring 63 has a larger internal diameter and is correspondingly thinner so that it can fit around extension 64 of the body which serves as its base. Resting on extension 64 and ring 63 is a thin ring 66, and positioned on this ring is another thin ring 67. Rings 61 and 66 as well as extension 64 have openings 62a therein which are in alignment so that bolts 62 can be passed through the openings. In order to accommodate the head of bolt 62, ring 67 has a depression molded in or cut away from its underside.

The rings described above can be fabricated, as by molding, from any suitable insulating material capable of withstanding the temperatures to be encountered. A preferred insulation is asbestos which has been mixed with a resin binder, e.g., a phenolic resin, to form a strong solid material.

From the foregoing discussion, it is apparent that the insulation rings can be readily placed around or removed from body 11. When securing the mixing apparatus in an operating position, thebody is initially placed on insulation ring 61 with the holes in ring 61 and extension 64 in alignment. Thereafter, ring 66 is added with its openings in alignment with the aforementioned holes. Bolts 64 are then positioned and secured to a suitable base. Ring 67 can now be placed in position after which the intermediate rings and top ring 58 are added.

Shaft 16 can be connected to any suitable motor which is capable of turning the shaft in either direction at variable known speeds. A variable speed reversible motor having a l horsepower rating can be used with advantage. A constant speed motor which is connected to shaft 16 through a gear train can also be employed. The gear train is capable of reducing the motor speed so as to rotate the shaft at a desired speed, such as from 5 to 50 revolutions per minute. When using this latter type of drive means, the mixing apparatus is mounted on the gear box (not shown) and shaft 68'is the output shaft connected to the gear train. Shaft 16 is connected to shaft 68 by means of a coupling device which consists of flanges or plate members 69 and 71 which are fixedly attached to the ends of shafts 16 and 68, respectively. The bottom side of flange 69 and the top side of flange 71 have corresponding square shaped depressions or cavities formed therein. An insulating material 72 ispositioned in the square depressions of the two flanges. The insulating material is square in shape and is of such a size that it fits tightly in the depressions, thereby coupling shaft 16 with shaft 68. It is to be understood that the depressions and insulating material can be other than square, e.g., triangular, rectangular or even an irregular shape. The thickness of the insulating material is such that the flanges are separated from one another, thereby preventing the flow of heat from shaft 16 to shaft 68. The insulating material described hereinabove can also be utilized in the coupling device.

The interior of container 33 is cup-shaped with its wall being inclined outwardlyfrom the vertical, for example, by about to The container or mixing cup and spiral rotor 39 are preferably fabricated of stainless steel for corrosion resistance a'hd nitride hardened for abrasion resistance. The mixing cup can be raised until it contacts the bottom of the rotor or lowered until pins 34 reach the bottom of their openings or the bottom of the cup contacts the bottom of cylindrical opening 12. Vertical movement of the mixing cup is accomplished by turning worm 52 which causes ring 49 to rotate. Since ring 49 cannot move vertically, its rotation results in the upward or downward movement of the mixing cup. By proceeding in this manner, it is possible to vary the spacing between the walls and bottom of the mixing cup and the ends and bottom of the rotor blades. Thus, by changing the speed of rotation of the rotor and the aforementioned spacing, it is possible to control the shear force to which an elastomer is subjected. In general, the rotor should be a ground fit with less than 0.001 inch clearance at the cup bottom and walls when the cup is fully raised. When the cup is lowered, the clearance will increase.

By referring to FIG. 2, a better understanding can be obtained of the configuration of spiral rotor 39 and the location of various other elements. In the normal mixing operation, the rotor turns :in a counterclockwise direction. A portion of the face or leading surface of each rotor blade extends downwardly as a vertical plane from outer side 73 of blade top 75. The outer end of the face of each blade presents a convex surface which slopes inwardly and downwardly from outer end 74 of blade top 75 to the edge represented by the broken line. The slope of the convex surface is such that it conforms to the shape of the interior of the mixing cup. Top 75 of each rotor blade is represented as being a horizontal surface, but it is preferably rounded to prevent material from collecting on the top of the rotor blades. The surface opposite face 73 is curved, presenting a concave surface 77 that slopes downwardly to a curved edge 77a that is in the same horizontal plane as the edge represented by the broken line. The under surface of the rotor, formed by the aforementioned horizontal planes, i.e., the bottom of the blades, and the circular flat surface surrounding the bottom of the rotor opening, is parallel to the bottom of the mixing cup. Because of the described structure, the materials to be mixed are sheared and kneaded by the rotating blades so as to provide a homogeneous mass or mixture. Reversal of the direction of the rotor, i.e., to a clockwise direction, results in the mixed materials being picked up by the edges of concave surface 77. As result of this action, the mixed materials can be recovered in quantitative yields.

In FIG. 2, the position of outlet 56, which was not visible in FIG. 1, can be seen. The heads of bolts 62 are also visible as well as washers 78 which are disposed between the heads and insulation: ring 66. Also, as depicted, worm 52 is attached to a shaft 79 by means of a screw or pin 80. A crank handle 81 is connected to the end of shaft 79 exteriorly of the insulation to provide means for turning the shaft. The shaft turns in and is supported in openings in insulation ring 58 and body 11, thereby maintaining worm 52 engaged with the gear teeth of ring 49.

A clearer understanding of the interior of the mixing apparatus can be obtained by referring to FIG. 3 which is a partial top view thereof with the mixing cup and insulation removed. In removing the cup, as shown in FIG. 1, it is first necessary to unscrew conical cap 44 after which ring 42 with attached pins 43 can be withdrawn. This permits rotor 39 to be removed from shaft 16. Referring also to FIG. 2, ring 58 is now removed to gain access to worm 52. Removal is readily accomplished since the opening or slot in the ring in which shaft 79 rides is in the shape of an inverted U extending to the bottom of the ring. Worm 52 can now be detached from shaft 79 by removing screw through opening 85 in the top of body 11. Shaft 79 can now be withdrawn through its opening in body 11. The worm now rests in the bottom of the opening which is semicircular in shape. The length and width of the opening is slightly larger than the length and diameter of the worm so that the worm can be moved sufficiently to permit its disengagement from the gear teeth of ring- 49. Worm 52 can now be recovered from its opening in the top of the body after which retainer ring 51 is unscrewed from body 11. The mixing cup with ring 49 in place and with pins 34 attached can now be lifted out of opening 12 in body 11. The mixing cup can be readily reassembled by following the foregoing steps in their reverse order. The positioning of the various elements will be apparent by comparing F IGS. l and 2 with F IG. 3. Particular attention is directed to semicircular grooves 85 in the side of shaft 16 that coincide with similar grooves in the wall of the rotor opening to form cylindrical openings in which pins 43 fit (see FIG. 1

Referring now to FIG. 4, there is illustrated a container 82 which can be attached to mixing cup 33. The container when attached makes it possible to conduct the'mixing operation in an inert atmosphere, such as argon or nitrogen, or under a vacuum. The container is made of glass, preferably a borosilicate glass, in order to withstand high temperatures, and is desirably in the shape of a dome. The bottom of dome 82 has a flange 83 which rests on the top of the wall of the mixing cup. In the bottom of flange 83, a circular groove, semicircular in cross section, is formed in which an ring seal 84 is positioned to provide a vacuum tight seal.

The dome is maintained in position on the mixing cup by a retaining means which comprises a retainer ring 86 that is threaded onto the outer wall of the cup. Attached to the top of the retainer ring by means of screws 87 is a flat ring 88. Ring 88 protrudes inwardly past the inner vertical wall of retainer ring 86. However, ring 88 has an inner diameter which is greater than the outer diameter of flange 83. This type of structure is necessary in order that flange 83 can pass through ring 88 in assemblying and disassemblying the dome. A wedge triangular shaped ring 89, which is split in two equal sections, is held in position between retainer ring 86 and the protruding edge of ring 88. The inner edge of ring 89 rests on a cushioning material 91 which in turn is positioned on flange 83. Triangular ring 89 is in two sections to permit its assembly and disassembly since it necessarily has a smaller diameter than flange 83 and, if in one piece, would not permit flange 83 to pass through. The cushion material is furnished to protect the glass flange and can be formed of any suitable fibrous or rubbery material. From the foregoing discussion, it is apparent that with the retainer ring and ring 88 in place on the end of the mixing cup, the dome with the cushioning material and sealing ring can be deposited on the mixing cup. The two sections of split ring 89 can now be inserted between cushioning material 91 and retainer ring 86 and its attached ring 88. Now when the retainer ring is screwed down down, the dome is held firmly in place. ln order to remove the dome, the steps described are followed in their reverse order.

Dome 82 is provided with a liquid port 90 and a gas port 92. The liquid port can be provided with a suitable closure means, such as a glass stopper. The gas port has a valve positioned therein that is illustrated as being a stopcork 93 of well known construction comprising a tapered valve member 94 having an opening therein. The tapered valve member is positioned in a seat which is contiguous with the gas port conduit. When the valve member is turned so that its opening is in line with the conduit, a gas can be introduced into or withdrawn from the dome. To prevent the flow of gas, it is only necessary to turn the valve member so that its opening is no longer in alignment with the conduit. When it is desired to operate under a vacuum, it is convenient to connect the liquid port to a vacuum pump and the gas port to a manometer to measure the vacuum.

Dome 82 is also provided with a means for introducing solid materials into the mixing cup while at the same time preventing the introduction of air. The solids introduction means comprises a glass conduit 96 which is flared at its outer end 97 to provide a spherical shaped seat 98. A shovel-like container 99, which can conveniently be in the shape of a shallow cup or pan, is connected to one end of rod 101. A hemispherical member 102 coincides with and is positioned in spherical shaped seat 98. The other end of rod 10] passes through hemispherical member 102 and is attached to the inside of handle 103. The handle is in turn attached to the hemispherical member. All elements of the solids introduction means as well as the liquid and gas ports are preferably formed of borosilicate glass. From the foregoing description, it is seen that the solids introduction means actually constitutes a ball and socket joint that permits movement of container 99 so that solids placed therein can be dumped into the mixing cup. A lubricant, such as a silicone oil, which also functions as a seal, is advantageously placed between seat 98 and hemispherical member 102.

The mixing apparatus of this invention possesses many advantages over those that have been previously used to mix small quantities of polymers and compounding ingredients. The polymers can be of a wide viscosity range. Either liquid or high viscosity polymers can be efficiently mixed and recovered in quantitative yields. The shearing action whereby the compounding ingredients are dispersed in the polymers can be varied by changing the rotor speed and/or by raising or lowering the mixing cup. Furthermore, the temperature of the mixing operation can be readily controlled from below room temperature to temperatures in the range of 400 to 600F. Since the mixing can be accomplished under a vacuum or in an inert atmosphere, the polymer mix is not subject to contamination. The mixing apparatus can be rapidly disassembled for cleaning and then readily assembled for continued use. Furthermore, because the apparatus makes possible the remote handling of the batch from commencement of the mixing operation until completion, the hazards of conventional mixers are not present.

As will be evident to those skilled in the art, various modifications of the invention can be made or followed in the light of the foregoing disclosure without departing from the spirit or scope of the invention lclaim:

l. A mixing apparatus comprising a body member having a vertical opening extending therethrough, said opening having a substantially circular cross section and its upper portion having a larger diameter than its lower portion; a vertical shaft rotatably positioned in said opening and extending through the upper and lower portions thereof; a container positioned in said upper portion of said body member, said container having an opening therein through which said shaft extends and in which said shaft is free to rotate and said container having an interior with inwardly sloping sides and a horizontal bottom; means for preventing said container from rotating; a mixing means fixedly attached to said shaft and disposed in said container, said mixing means being in the form of a rotor having sloping sides conforming to the sloping sides of said container; and means operatively connected to said body and said container for raising and lowering said container to a fixed position relative to said mixing means.

2. A mixingapparatus according to claim 1 in which a heat exchange means is operatively connected to said body member.

3. A mixing apparatus according to claim 2 in which an insulating material encompasses the exterior of said body member.

4. A mixing apparatus according to claim 1 in which a drive shaft is operatively connected to the lower end of said shaft.

5. A mixing apparatus comprising a body member having a vertical opening extending therethrough, said opening having a circular horizontal cross section and its upper portion having a larger diameter than its lower portion; a vertical shaft positioned in said opening and extending through said upper and lower portions thereof; a first set of roller bearings disposed between a pair of races, one race being positioned against said shaft and the other race being positioned against the wall of said lower portion of said opening; a second set of roller bearings positioned below said first set and disposed between a pair of races, one race being positioned against said shaft and the other race being positioned against. the wall of said lower portion of said opening; an open top container substantially cylindrical in shape and having a cup-shaped interior and an opening formed in its base through which said vertical shaft extends, said container being positioned in said upper portion of said vertical opening in said body member; threads formed in and around the outer surface of the upper portion of said, container, a plurality of first vertical holes formed in said container and extending upwardly from its base and space around said base adjacent its periphery; a plurality of second vertical holes formed in said body member and extending downwardly through a portion thereof adjacent said lower portion of said opening, each of said second holes being in vertical alignment with one of said first holes so as to form a plurality of pairs of first and second holes; a pin member positioned in each pair of said first and second holes, theupper end of said pin member being fixedly positioned in said first hole and movably positioned in said second hole, the length of said pin member being less than the total length of said first and second holes; a ring member having threads formed in its interior surface and teeth formed in its exterior surface, said ring member being threadedly mounted in a fixed position on the exterior of said container; a worm whose thread meshes with said teeth of said ring member, said worm being horizontally positioned in said body member and adapted to be turned therein by a horizontal shaft connected to said worm and extending exteriorly from said body member; and a rotor positioned within said container and fixedly attached to said vertical shaft.

6. A mixing apparatus according to claim 5 in which a heat exchange means is operatively connected to said body member and an insulating material encompasses the exterior of said body member.

7. A mixing apparatus according to claim 6 in which said heat exchange means comprises a spiral groove formed in and encircling the exterior surface of said body member; sheet metal covering said groove, thereby forming a continuous passageway around said body member; an inlet conduit attached to one end of said passageway; and an outlet conduit attached to the other end of said passageway.

8. A mixing apparatus according to claim 6 in which said heat exchange means comprises a coil of metal tubing positioned between said body member and said insulating material.

9. A mixing apparatus according to claim 5 in which a glass chamber is fixedly attached to an upper portion of said container, said container having a liquid port, a gas port, and a means for introducing solid materials while excluding admission of air.

10. A mixing apparatus according to claim 9 in which said means for introducing solid material comprises a glass conduit connected to said chamber, the outer end of which is flared to provide a spherical shaped seat; a glass, shovel-like container; a glass rod having one of its ends connected to said container; a glass hemispherical member coinciding with and being positioned in said spherical shaped seat and having the other end of said glass rod connected thereto; and :means for moving said hemispherical member in said seat. I

l l. A mixing apparatus according to claim 5 in which the lower end of said vertical shaft is attached to a drive shaft by a coupling means.

12. A mixing apparatus according to claim 11 in which said coupling means comprises a first flange fixedly attached to the end of said vertical shaft, the bottom side of said flange having a depression formed therein; a second flange fixedly attached to the end of said drive shaft, the top side of said flange having a depression formed therein directly opposite the depression in said first flange; and a solid insulation material tightly positioned in said depressions, said material having a thickness sufficient to maintain said flanges separated from one another and having the same shape as said shape as said depressions, said shape being such that said material prevents relative movement between said flanges.

13. A mixing apparatus comprising a body member having a vertical opening extending therethrough, said opening having a substantially circular cross section and its upper portion having a larger diameter than its lower portion, a vertical shaft rotatably positioned in said opening and extending through the upper an lower portions thereof; a heat exchange means operatively connected to said body member; a container positioned in said upper portion of said body member, said container having an opening therein through which said shaft extends and in which said shaft is free to rotate; means for preventing said container from rotating; a mixing means fixedly attached to said shaft and disposed in said container; means operatively connected to said body and said container for raising and lowering said container to a fixed position relative to said mixing means; and a glass chamber fixedly attached to an upper portion of said container, said chamber having a liquid port, a gas port and a means for introducing solid materials while excluding admission of air.

14. A mixing apparatus comprising a body member having a vertical opening extending therethrough, said shaft and disposed in said container, said rotor comprising a pair of oppositely positioned blades, each having a convex outer surface that slopes inwardly in conformity with the sloping sides of said container and opposite each convex outer surface a concave surface sloping downwardly toward said horizontal bottom; and means operatively connected to said body and said container for raising and lowering said container to a fixed position relative to said rotor. 

1. A mixing apparatus comprising a body member having a vertical opening extending therethrough, said opening having a substantially circular cross section and its upper portion having a larger diameter than its lower portion; a vertical shaft rotatably positioned in said opening and extending through the upper and lower portions thereof; a container positioned in said upper portion of said body member, said container having an opening therein through which said shaft extends and in which said shaft is free to rotate and said container having an interior with inwardly sloping sides and a horizontal bottom; means for preventing said container from rotating; a mixing means fixedly attached to said shaft and disposed in said container, said mixing means being in the form of a rotor having sloping sides conforming to the sloping sides of said container; and means operatively connected to said body and said container for raising and lowering said container to a fixed position relative to said mixing means.
 2. A mixing apparatus according to claim 1 in which a heat exchange means is operatively connected to said body member.
 3. A mixing apparatus according to claim 2 in which an insulating material encompasses the exterior of said body member.
 4. A mixing apparatus according to claim 1 in which a drive shaft is operatively connected to the lower end of said shaft.
 5. A mixing apparatus comprising a body member having a vertical opening extending therethrough, said opening having a circular horizontal cross section and its upper portion having a larger diameter than its lower portion; a vertical shaft positioned in said opening and extending through said upper and lower portions thereof; a first set of roller bearings disposed between a pair of races, one race being positioned against said shaft and the other race being positioned against the wall of said lower portion of said opening; a second set of roller bearings positioned below said first set and disposed between a pair of races, one race being positioned against said shaft and the other race being positioned against the wall of said lower portion of said opening; an open top container substantially cylindrical in shape and having a cup-shaped interior and an opening formed in its base through which said vertical shaft extends, said container being positioned in said upper portion of said vertical opening in said body member; threads formed in and around the outer surface of the upper portion of said container, a plurality of first vertical holes formed in said container and extending upwardly from its base and space around said base adjacent its periphery; a plurality of second vertical holes formed in said body member and extending downwardly through a portion thereof adjacent said lower portion of said opening, each of said second holes being in vertical alignment with one of said first holes so as to form a plurality of pairs of first and second holes; a pin member positioned in each pair of said first and second holes, the upper end of said pin member being fixedly positioned in said first hole and movably positioned in said second hole, the length of said pin member being less than the total length of said first and second holes; a ring member having threads formed in its interior surface and teeth formed in its exterior surface, said ring member being threadedly mounted in a fixed position on the exterior of said container; a worm whose thread meshes with said teeth of said ring member, said worm being horizontally positioned in said body member and adapted to be turned therein by a horizontal shaft connected to said woRm and extending exteriorly from said body member; and a rotor positioned within said container and fixedly attached to said vertical shaft.
 6. A mixing apparatus according to claim 5 in which a heat exchange means is operatively connected to said body member and an insulating material encompasses the exterior of said body member.
 7. A mixing apparatus according to claim 6 in which said heat exchange means comprises a spiral groove formed in and encircling the exterior surface of said body member; sheet metal covering said groove, thereby forming a continuous passageway around said body member; an inlet conduit attached to one end of said passageway; and an outlet conduit attached to the other end of said passageway.
 8. A mixing apparatus according to claim 6 in which said heat exchange means comprises a coil of metal tubing positioned between said body member and said insulating material.
 9. A mixing apparatus according to claim 5 in which a glass chamber is fixedly attached to an upper portion of said container, said container having a liquid port, a gas port, and a means for introducing solid materials while excluding admission of air.
 10. A mixing apparatus according to claim 9 in which said means for introducing solid material comprises a glass conduit connected to said chamber, the outer end of which is flared to provide a spherical shaped seat; a glass, shovel-like container; a glass rod having one of its ends connected to said container; a glass hemispherical member coinciding with and being positioned in said spherical shaped seat and having the other end of said glass rod connected thereto; and means for moving said hemispherical member in said seat.
 11. A mixing apparatus according to claim 5 in which the lower end of said vertical shaft is attached to a drive shaft by a coupling means.
 12. A mixing apparatus according to claim 11 in which said coupling means comprises a first flange fixedly attached to the end of said vertical shaft, the bottom side of said flange having a depression formed therein; a second flange fixedly attached to the end of said drive shaft, the top side of said flange having a depression formed therein directly opposite the depression in said first flange; and a solid insulation material tightly positioned in said depressions, said material having a thickness sufficient to maintain said flanges separated from one another and having the same shape as said shape as said depressions, said shape being such that said material prevents relative movement between said flanges.
 13. A mixing apparatus comprising a body member having a vertical opening extending therethrough, said opening having a substantially circular cross section and its upper portion having a larger diameter than its lower portion, a vertical shaft rotatably positioned in said opening and extending through the upper an lower portions thereof; a heat exchange means operatively connected to said body member; a container positioned in said upper portion of said body member, said container having an opening therein through which said shaft extends and in which said shaft is free to rotate; means for preventing said container from rotating; a mixing means fixedly attached to said shaft and disposed in said container; means operatively connected to said body and said container for raising and lowering said container to a fixed position relative to said mixing means; and a glass chamber fixedly attached to an upper portion of said container, said chamber having a liquid port, a gas port and a means for introducing solid materials while excluding admission of air.
 14. A mixing apparatus comprising a body member having a vertical opening extending therethrough, said opening having a substantially circular cross section and its upper portion having a larger diameter than its lower portion, a vertical shaft rotatably positioned in said opening and extending through the upper and lower portions thereof; a container positioned in said upper portion of said body member, saiD container having an opening therein through which said shaft extends and in which said shaft is free to rotate and said container having an interior with inwardly sloping sides and a horizontal bottom; means for preventing said container from rotating; a rotor fixedly attached to said shaft and disposed in said container, said rotor comprising a pair of oppositely positioned blades, each having a convex outer surface that slopes inwardly in conformity with the sloping sides of said container and opposite each convex outer surface a concave surface sloping downwardly toward said horizontal bottom; and means operatively connected to said body and said container for raising and lowering said container to a fixed position relative to said rotor. 